Differences in local anesthetic effects of optically active isomers of local anesthetic compounds

Abstract

Amino-amide type local anesthetics, which have been most frequently used in clinical anesthesia are lidocaine, prilocaine, bupivacaine, ropivacaine and mepivacaine. These drugs show different clinical properties depending on their structures. In clinical praxis bupivacaine and mepivacaine are used as racemic mixtures. The stereochemistry of these two local anesthetic affects considerably the pharmacological action and toxicity. R(+) bupivacaine is 7 times more potent in blocking the sodium channels than the S(-)-enantiomer. Levobupivacaine and ropivacaine provide nerve blocking characteristics similar to those of racemic bupivacaine in almost all regional anesthesia techniques. The potency of bupivacaine is proportional to the toxic effects on cardiovascular system and central nervous system. Since these local anesthetic compounds are toxic, causing cardiovacular and central-nervous disorders, the therapeutic blood-plasma/serum concentrations should not exceed certain limits. © 2006 Taylor and Francis Group, LLC.